This invention relates to compositions useful for the prevention and treatment of coccidiosis in animals, methods of using the compositions and animal comestibles containing the compositions.
Coccidiosis is a troublesome disease which afflicts animals such as companion animals and ranch or farm animals raised commercially as a food source. The disease is caused by protozoal parasites called coccidia, which belong to the genus Eimeria. Typically, the infection occurs when the animal ingests food, water or fecal material contaminated with Eimeria organisms in the sporulated oocyst stage and the ingested oocysts enter the intestine and the cecum. The infection results in the destruction of the intestinal linings of the host animal, often leading to death. Even if the animals survive the infection, they grow more slowly than normal and the feed efficiency is adversely affected, causing significant economic losses if the infection involves large populations of food animals such as chickens, turkeys, geese, ducks, cattle, sheep and pigs.
Coccidiostatic agents are available for the prevention or treatment of coccidiosis. However, many of these agents are not entirely satisfactory in maintaining feed efficiency and weight gain, and others have very narrow safety and efficacy ranges and thus pose a risk to the animals being treated. Moreover, to a greater extent Eimeria organisms are developing resistance to the more frequently used coccidiostatic agents available on the market, thus limiting the effectiveness of such agents.
A widely used commercially available class of coccidiostats are those belonging to the group of polyether antibiotics isolated from various strains of bacteria. These substances are characterized by cyclic ether moieties in their chemical structures and are also commonly referred to as "ionophores" because of what is believed to be their transport-inducing mode of action. Among the more notable examples are lasalocid, monensin, salinomycin, lonomycin, narasin and maduramycin.
Non-ionophorous anticoccidial agents include those based on combinations of a sulfanilamide antibiotic and a potentiating 2,4-diamino-5-(2',4',5'-trisubstituted benzyl) pyrimidine. Combinations of this type are described in U.S. Pat. No. 3,461,206 (Hoffer and Mitrovic).
Potentiated sulfanilamides have experienced limited commercial use as anticoccidials due to their more moderate effectiveness compared to ionophores. Ionophorous anticoccidials, while possessing very good coccidiocidal activity as a class, often pose difficulties in use because of their relatively narrow range of efficacy and the development of resistance to them.